want a good kit on a budget

[dnmun]

well what was i to think with the big johnny walker? my apologies, really. dm

 

[Jethro56]

Kinda a rule of thumb for sizing batteries is 35 watt hours per mile. Most people do better but I'd rather oversize for better battery life. So lets say you get a 10 amper hour 12S lipo setup. The cells are rated to be charged to 4.2V but they don't last as long as if you only charge them to 4.1V . So you start out with 12 X 4.1V or 49.2V. As you go along the voltage drops. Dogman suggests allowing the cells to only drop to 3.65V so 12 X 3.65 = 43.8V . To find watt hours multiply voltage X capacity. Lets call this a 44.4V battery. You've dropped the full capacity to 80% so 44.4 X 8 = 355 watt hours. So 10 miles would be a conservative range.

Note how the voltage goes down as you ride. I've tested my Hobbie King packs and know their pretty good.(If you watched the video's I suggested. I'm saying all the cells discharge and charge at close to the same rate) I have a display of pack voltage. If it gets down to 45V I know I'd better do most of the work by slowing down and pedaling harder. I'm the BMS.

I have a 20aH 12s pack I've went 30 miles and haven't gone below 45V. That's riding 22 mph and pedaling at a rate I could maintain for hours.

You won't pull 20 amps continuously unless going uphill. I guessing as no hills here.

 

[wesnewell]

So what would you guys recomend for the battery pack? looking at 20 sustained mph for 10 miles on a 500w mac motor. is this a viable set up for what Im looking for? or is there a better option at 48v? what should I get for a controller? BMS or not? links pls

also, if I get a, say, 20 amp controller, that means i could discharge at 2C? and at that rate its gone in 30 min? Or I could get a 200 amp controller and fly like the wind at 20C for a whopping 3 minutes? to increase that to 1 hour Id need to go to 20 Ah battery set up? At the same rated batteries, It would then take them one hour to fully recharge again at 1C? C rates still confuse me a bit.

A 10ah 12s lipo pack will get you about 20 miles at 20mph. No BMS needed or wanted. A vom or watt meter to monitor voltage is nice but not required when using 12s lipo on a standard 48V controller as the controllers lvc will shut you down before you damage the battery.
A 200A controller won't get you any faster than a 20A controller. It will just get you to top speed faster. Actually a 200A controller on a 48V ebike is ridiculous anyway. Max you would ever normally want would be 30-50A. I personally wouldn't want one less than 30A, But I'm 270lbs and and a little extra torque helps. Amps adds torque. Voltage adds top speed along with a little torque. C rates are the amp rates for the battery. A motor drawing 30A from a 10ah battery is a 3C rate (30/10=3). Multiple C rate times the battery ah to get max output amps. IOW's 10ah of 20C lipo it rated to put out 200A. Now cut that in half and you should never have a problem.

 

[dogman dan]

10 ah will get you 10 miles easily. At 20 mph, likely about 15 miles unless hilly.

But a less expensive lifepo4 battery such a ping should be 15 ah becasue of the lower discharge rate for those types. Better stuff, like the cellman A123's or hobby king lipo cold be much smaller. like 9-10 ah.

 

[e-beach]

Ok,
From nubee to nubee (I have only been at it for a month myself) let me just say this….

“You have to build one to know how to build one.” :wink:

There is a lot of good advice in the previous comments, but it might take a while until it all starts making since. And some of the aforementioned kits might be better for you then mine, but let me tell you what I did.

I bought:

1 - 36v 800w front wheel kit from Yescomusa. $250.00

3-12v 12 Ah Sealed Lead Acid batteries because that is all the money I had at the moment. $35.00 each plus tax. $115.00

1-Trek 800 suspension-less mountain bike with a big triangle. $55.00

(Why suspensionless? Because the price was right).

Total initial investment: $420.00

I initially bought the Yescomusa front wheel kit because it was inexpensive and simple. I wasn’t sure if I would be able to get the gears adjusted properly with a rear wheel kit, so I satisfied myself with simplicity. Now that I have done this bike, I realize that a rear wheel hub motor is probably better because:

A) There is less chance of the wheel dropping out of the back mount.
B) It is much better to have a front disk break for maximum stopping power.

The Golden Motor that came with my kit has no place to attach a disk brake. Instead of making one, I will just upgrade to a rear hub motor on my next build in the future.

The instillation took me a couple of days of fiddling to see how I wanted to mount the batteries. The rack that came with the kit was flimsy and didn’t fit my bike well, but I used it anyway for my first trials. The battery bag that came with the kit didn’t fit my SLS very well, and the main zipper came off almost immediately. It wasn’t like the zipper teeth ripped, the zipper just sort of fell off like it wasn’t the right size for the zipper teeth.

None- the-less, I bungee-corded it all together and it worked for testing.

However, on my first hill the 30 amp fuse that came with the kit blew. Off to the auto parts store I went to get a real fuse. With the fuse replaced, the bike was working again. I later found that the fuse holder that came with the kit was beginning to melt so I replaced that as well.

I also got my first flat tire yesterday. My tires need some air, so I looked at the side of the tire for the proper inflation numbers. They were probably on the tire…..if you could read Chinese. :x

Anyway I put air into it. I could still squeeze the tire a little bit so I am sure I didn’t over fill it. As I was putting my pump away, there was a “POP…HISSSSSSS!”

I was thinking that it was a cheap Chinese inner tube until I opened it up and found that it had no rim liner?!?! The rim cut into the inner tube and popped it.

2 rim liners and an inner tube later it now holds 60 lbs of pressure no problem.

OK, like you, I wanted my ebike to look good. I got rid of the bag and took a plastic tool box and mounted it to the rack. My batteries and controller fit snugly with some padding and it looked very clean. But 25+ pounds that high on the back of the bike, especially on a flimsy rack, ended up contributing to a hard crash I took in my first week. (Cracked rib, bruises, road rash etc..)

Back to the drawing board…..

As stated, I original bought my bike because it had a large triangle. I envisioned my batteries being in the triangle in the first place. Somehow I got side-tracked by the simplicity of putting them on my rack…never again!

I built a plywood rack for my batteries and controller and it completely changed how the bike rides. Much-more stable now!!! Huge difference!!!

My bike is up and running now, but it is very-very heavy with the lead batteries. My range is about 12 miles max with some light peddling, and that is with 50 foot elevation going to the beach, and 150 feet coming back. 200 ft total. (There are hills between me and the beach.) Even with the weight, I can get this ebike going fast enough so that none of the experienced, rock-hard-calved, road cycles can drop me on the flats, and I pass them on the hills. They don’t like it much.

You mentioned that you didn’t like the clap-board look of some ebikes, well, how creative are you at modification? Or, are you willing to pay to have some welding done, or purchase triangle bags…etc.
You could also configure your own cells to fit your bike just right for you, if you want to learn how...

Also, you were wondering about a torque arm. Think of it this way. Is it worth $20 or $30 to make sure your wheel doesn’t come flying off when you are going 30 mph? I can tell you from first hand experience street is harder then bone.

You probably have stories yourself.

Anyway to finish this long post…..

My Conclusions:

Start with a rear wheel hub motor. It is less likely to break off the bike and you might be able to upgrade to a disk break in the front.

Mount your batteries in the triangle from the beginning for best stability.

My 36v 800w system is good enough for my 205 lbs plus 25 lbs of lead batteries and steel bicycle frame moving about 20+ mph. (Some say my controller and motor will handle 48v “no problem”
So when I upgrade to better batteries, I will go with 48 volts.

If you want to go Yescomusa, a 48v 1000w rear wheel kit might be a good choice, just remember that the hub itself is kind of heavy so bike tricks are probably out.

Will my Yescomusa kit work in snow? I don’t know. We don’t get snow around here and I walk when it rains. A Canadian would be a better person to ask about a snow-ebike.

If you use a Yescomusa kit, change tires to something that is suitable for your environment. Fat tires make for a more comfortable ride. Make sure that the rim has a rim liner. Throw away the bag, the fuse and fuse holder. Replace them with a suitable fuse and holder from an auto parts store.

For any kit you install, get triangle bag or make a real mount inside your triangle for your batteries. I have found that 4.25 inches is as wide as I want. That way my legs don’t rub when I peddle. When I upgrade to LiFePo4’s my pack will be no wider then about 4 inches which will give just enough room for cover to my mounting system.

When I upgrade I will be going with LiFePo4 so I don’t have to worry about fire when I come home tipsy and just want to plug it in and go to bed.

Know that at some point you will need electronics for reading your volts, amps and speed. Those in themselves could be as much as $200.00 all-together.

And finally, once you get your bike up and running, and are having a great time on it, don’t hold back on dreaming about your first frankenbike….we all do it!

Hope this helps.

 

[wesnewell]

None of the 3 yescomusa kits I've bought has had rim tape. A $2 roll of friction tape fixes that in a minute. And the fuse holder sucks too, but I didn't have a problem with it although I've replaced the battery wiring and used a blade fuse. There's a kit for rear disc brakes you can get from goldenmotor. Don't see a mount for disc brakes on my front motor either, but I use regen braking on both mine.

 

[jkbrigman]

Ok,
From nubee to nubee (I have only been at it for a month myself) let me just say this…. “You have to build one to know how to build one.” :wink:

There is a lot of good advice in the previous comments, but it might take a while until it all starts making since. And some of the aforementioned kits might be better for you then mine, but let me tell you what I did......

Excellent post e-beach! Superb example of why experience counts for (almost) everything when building an ebike!

JKB

 

[electr0n]

I suggest you get a direct drive motor for riding in winter. I have no experience with geared motors at all but I can tell you my direct drive crystalyte 407 front hub motor works very well in the snow and rain. Maybe cellman or someone with experience could say how well the geared motors work in rain and snow? I got the front motor for simplicity to begin with but my next purchase will be a rear motor for safety reasons more than anything else. Although I have never had a problem running my front motor at 66.6v and 20 amps even without torque arms and I've been riding it for a couple years now. I do have a cheap steel suspension fork. Generally people advise against that type of setup but it''s been fine for me and I believe dogman also is setup with a front motor as well. I wouldn't rule out a front motor build as a newbie if you're mechanically weary like I am.

I would say you should get a controller rated higher than 20 amps for sure, you'll probably want more power once you get a taste. Also don't bother with the lead acid batteries unless they are almost free. Lipo all the way. You can get them pretty cheap from hobby king with a cheapie charger and you can salvage an old pc power supply from your goodwill to power the charger. The great thing with the lipo is they're super light and they're modular. You can start off with two 5S 20C packs for a 38v pack. Then when you get more cash later on you can add another battery or two in series when you want to go faster, or you can wire them up in parallel for when you want more range. You should be able to put together a very nice setup for under $700. Just make sure you don't limit yourself with a 20 amp controller and I would suggest also getting a controller that can handle up to 72 volts.

 

[Kinni420]

quicky reply on the rim tape deal. no rim tape = popped inner tube. cheapest rim tape is straight black electrical tape, tighter you pull on the tape thinner it gets so good for a 26x2.125 to a 700c rim, wont rot under pressure as much as fiber tapes, wont burst under 125 psi. 2 full wraps around the diameter and youre good for life. I havent replaced the electrical tape on my cruiser in over 20 years.

going into the posts since my last, great info, but what I learned going into my first computer build before I bought everything led me into a fantastic computer I use for the best games out there even though in about 10 days it will be 3 years old. Its still upgradeable to the latest stuff although I havent reached a peak yet that will hold me back. I could ramble on and on about my SSD and 16gb ram but who cares, what Im after atm is the best, affordable, fastest commuter bike out there and you guys are giving me lots of great advice. Im settled on getting lipo, count on it. I have the time and dedication to make lipos work and work well with little abuse. from what Ive read and what u guys have posted, 48v 15aH, looks solid and prepared to spend the money on the packs to get this done but it has to fit in the triangle. I dont want any handling issues as agressive as I am on my bikes (I true my wheels at least once a month due to this) For those that dont understand how much rear end weight cant affect preformance, stick 2 car batteries on ur bike rack and try to take a corner at 20. Unless u counterweight the front end, you're going to lose traction and smack your elbow and chin into the pavement.


ok todays question.....someone mentioned capacity in cold weather. I dont keep my bike outside, I can charge outside fine, but someone said half capacity in cold....we all know cold makes everything run slower. colder makes molecules slower- hotter faster. but...If I take a stack of lipos from inside at 70 F to outside at 28 f for 15 minutes, will I really lose that much capacity in an insulated ammo box?/triangle bag? I doubt theyd get much colder in 15 min. in fact from use Id think they'd actually get warmer due to molecular activity.

 

[Kinni420]

PC power supply, hmm what a great Idea! Being that I work in a thrift store as the electronics guy I get junk computers all the time. I also know how to remove them and make em work outside of the box I would assume higher wattage to be better? most store bought computers only run around a 250-350w power supply. My own hand built computer is running a 1000w.

 

[dogman dan]

If you bring your lipo out from a warm inside, then put them in an insulated box/bag, you shouldn't see too much less capacity. Perhaps some slower because of cold wiring on the bike, but not that much less range.

I get affected by cold because my lipo mount is built more with being a heat sink in mind. 95% of riding is done at 50-110F.

Nothing particularly wrong with the yesa kit, or similar cheap deals. You sound quite capable of replacing flaky connectors or whatever. We just tend to send most noobs to a vendor with USA based customer service if they can afford the extra $100.

 

[Jethro56]

PC power supply, hmm what a great Idea! Being that I work in a thrift store as the electronics guy I get junk computers all the time. I also know how to remove them and make em work outside of the box I would assume higher wattage to be better? most store bought computers only run around a 250-350w power supply. My own hand built computer is running a 1000w.

Check out the 24V rating. That will be much less. That was my problem with using an old compaq server P.S. I bought a used true Meanwell 500W P.S. on EBay ~$60 shipped.

 

[dogman dan]

True enough, depending on your charger setup, you may want a large 48v power supply for bulk charging, or a 24v power supply for running a larger wattage RC charger.

Definitely you can get by in the beginning with a scavanged PS and smaller cheaper RC charger. Just avoid the super cheezy 50 watt chargers, and quattro chargers that are 4 of the cheeze chargers.

 

[Kinni420]

starting a new post for this topic. Cuz budget is blown out the window. too addicted...will edit to place a link

here it is

http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=36799